scholarly journals Determinants of attenuation in the envelope protein of the flavivirus Alfuy

2011 ◽  
Vol 92 (10) ◽  
pp. 2286-2296 ◽  
Author(s):  
Natalie A. Prow ◽  
Fiona J. May ◽  
Daniel J. Westlake ◽  
Robert J. Hurrelbrink ◽  
Rebecca M. Biron ◽  
...  
Keyword(s):  
Infectious Clone ◽  
Glycosylation Site ◽  
Protein Glycosylation ◽  
Hinge Region ◽  
Wild Type ◽  
E Proteins ◽  
Time To Death ◽  
Naturally Occurring ◽  
High Doses ◽  
Delayed Time

Murray Valley encephalitis virus (MVEV) is a mosquito-borne flavivirus endemic to Australia and Papua New Guinea. Most strains of MVEV cause potentially fatal cases of encephalitis in humans and horses, and have been shown to be highly neuroinvasive in weanling mice. In contrast, the naturally occurring subtype Alfuy virus (ALFV) has never been associated with human disease, nor is it neuroinvasive in weanling mice, even at high doses. To identify viral factors associated with ALFV attenuation, a chimeric infectious clone was constructed containing the structural genes premembrane (prM) and envelope (E) of ALFV swapped into the MVEV genome. The resulting virus (vMVEV/ALFVstr) was no longer neuroinvasive in mice, suggesting that motifs within prM–E of ALFV confer attenuation. To define these motifs further, mutants were constructed by targeting divergent sequences between the MVEV and ALFV E proteins that are known markers of virulence in other encephalitic flaviviruses. MVEV mutants containing a unique ALFV sequence in the flexible hinge region (residues 273–277) or lacking the conserved glycosylation site at position 154 were significantly less neuroinvasive in mice than wild-type MVEV, as determined by delayed time to death or increased LD50. Conversely, when the corresponding MVEV sequences were inserted into the vMVEV/ALFVstr chimera, the mutant containing the MVEV hinge sequence was more neuroinvasive than the parental chimera, though not to the same level as wild-type MVEV. These results identify the hinge region and E protein glycosylation as motifs that contribute to the attenuation of ALFV.

scholarly journals Polysaccharides and virulence of Burkholderia pseudomallei

2007 ◽  
Vol 56 (8) ◽  
pp. 1005-1010 ◽  
Author(s):  
M. Sarkar-Tyson ◽  
J. E. Thwaite ◽  
S. V. Harding ◽  
S. J. Smither ◽  
P. C. F. Oyston ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Capsular Polysaccharide ◽  
Gene Clusters ◽  
Type I ◽  
Wild Type ◽  
Time To Death ◽  
Type Iii ◽  
Type Iv ◽  
Mutant Strains ◽  
Delayed Time

Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease of humans and animals. Gene clusters which encode capsular polysaccharide (type I O-PS) and LPS (type II O-PS), both of which play roles in virulence, have previously been identified. Here, the identification of two further putative clusters, type III O-PS and type IV O-PS, is reported. Mice challenged with type III O-PS or type IV O-PS mutants showed increased mean times to death (7.8 and 11.6 days) compared to those challenged with wild-type B. pseudomallei (3 days). To investigate the possible roles of polysaccharides in protection, mice were immunized with killed cells of wild-type B. pseudomallei or killed cells of B. pseudomallei with mutations in the O antigen, capsular polysaccharide, type III O-PS or type IV O-PS gene clusters. Immunization with all polysaccharide mutant strains resulted in delayed time to death compared to the naïve controls, following challenge with wild-type B. pseudomallei strain K96243. However, immunization with killed polysaccharide mutant strains conferred different degrees of protection, demonstrating the immunological importance of the polysaccharide clusters on the surface of B. pseudomallei.

scholarly journals N-Linked Glycosylation of West Nile Virus Envelope Proteins Influences Particle Assembly and Infectivity

2005 ◽  
Vol 79 (21) ◽  
pp. 13262-13274 ◽  
Author(s):  
Sheri L. Hanna ◽  
Theodore C. Pierson ◽  
Melissa D. Sanchez ◽  
Asim A. Ahmed ◽  
Mariam M. Murtadha ◽  
...  
Keyword(s):  
West Nile Virus ◽  
Envelope Proteins ◽  
Glycosylation Site ◽  
Protein Glycosylation ◽  
E Proteins ◽  
Virus Envelope ◽  
West Nile ◽  
Particle Assembly ◽  
E Protein ◽  
The Impact

ABSTRACT West Nile virus (WNV) encodes two envelope proteins, premembrane (prM) and envelope (E). While the prM protein of all WNV strains contains a single N-linked glycosylation site, not all strains contain an N-linked site in the E protein. The presence of N-linked glycosylation on flavivirus E proteins has been linked to virus production, pH sensitivity, and neuroinvasiveness. Therefore, we examined the impact of prM and E glycosylation on WNV assembly and infectivity. Similar to other flaviviruses, expression of WNV prM and E resulted in the release of subviral particles (SVPs). Removing the prM glycosylation site in a lineage I or II strain decreased SVP release, as did removal of the glycosylation site in a lineage I E protein. Addition of the E protein glycosylation site in a lineage II strain that lacked this site increased SVP production. Similar results were obtained in the context of either reporter virus particles (RVPs) or infectious lineage II WNV. RVPs or virions bearing combinations of glycosylated and nonglycosylated forms of prM and E could infect mammalian, avian, and mosquito cells (BHK-21, QT6, and C6/36, respectively). Those particles lacking glycosylation on the E protein were modestly more infectious per genome copy on BHK-21 and QT6 cells, while this absence greatly enhanced the infection of C6/36 cells. Thus, glycosylation of WNV prM and E proteins can affect the efficiency of virus release and infection in a manner that is cell type and perhaps species dependent. This suggests a multifaceted role for envelope N-linked glycosylation in WNV biology and tropism.

scholarly journals Involvement of oligomerization, N-glycosylation and sialylation in the clearance of cholinesterases from the circulation

1995 ◽  
Vol 311 (3) ◽  
pp. 959-967 ◽  
Author(s):  
C Kronman ◽  
B Velan ◽  
D Marcus ◽  
A Ordentlich ◽  
S Reuveny ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Half Life ◽  
Sharp Decrease ◽  
Life Time ◽  
Absolute Number ◽  
Glycosylation Site ◽  
Protein Glycosylation ◽  
Wild Type ◽  
Attachment Sites ◽  
Glycosylation Sites

The possible role of post-translational modifications such as subunit oligomerization, protein glycosylation and oligosaccharide processing on the circulatory life-time of proteins was studied using recombinant human acetylcholinesterase (rHuAChE). Different preparations of rHuAChE containing various amounts of tetramers, dimers and monomers are cleared at similar rates from the circulation, suggesting that oligomerization does not play an important role in determining the rate of clearance. An engineered rHuAChE mutant containing only one N-glycosylation site was cleared from the circulation more rapidly than the wild-type triglycosylated enzyme. On the other hand, hyperglycosylated mutants containing either four or five occupied N-glycosylation sites, analagous to those present on the slowly cleared fetal bovine serum acetylcholinesterase (FBS-AChE), were also cleared more rapidly from the bloodstream than the wild-type species. Furthermore, the two different tetraglycosylated mutants were cleared at different rates while the pentaglycosylated mutant exhibited the most rapid clearance profile. These results imply that though the number of N-glycosylation sites plays a role in the circulatory life-time of the enzyme, the number of N-glycan units in itself does not determine the rate of clearance. When saturating amounts of asialofetuin were administered together with rHuAChE, the circulatory half-life of the enzyme was dramatically increased (from 80 min to 19 h) and was found to be similar to that displayed by plasma-derived cholinesterases while desialylation of these enzymes caused a sharp decrease in the circulatory half-life to approximately 3-5 min. Determination of the average number of sialic acid residues per enzyme subunit of the five different N-glycosylation species generated, revealed that the rate of clearance is not a function of the absolute number of appended sialic acid moieties but rather of the number of unoccupied sialic acid attachment sites per enzyme molecule. Specifically, we demonstrate an inverse-linear relationship between the number of vacant sialic acid attachment sites and the values of the enzyme residence time within the bloodstream.

scholarly journals Importance of Conserved Cysteine Residues in the Coronavirus Envelope Protein

2008 ◽  
Vol 82 (6) ◽  
pp. 3000-3010 ◽  
Author(s):  
Lisa A. Lopez ◽  
Ambere J. Riffle ◽  
Steven L. Pike ◽  
Douglas Gardner ◽  
Brenda G. Hogue
Keyword(s):  
Infectious Clone ◽  
Virus Production ◽  
Wild Type Virus ◽  
Cysteine Residues ◽  
Wild Type ◽  
E Proteins ◽  
Triple Mutant ◽  
Hydrophobic Domain ◽  
Extracellular Virus ◽  
E Protein

ABSTRACT Coronavirus envelope (E) proteins play an important, not fully understood role(s) in the virus life cycle. All E proteins have conserved cysteine residues located on the carboxy side of the long hydrophobic domain, suggesting functional significance. In this study, we confirmed that mouse hepatitis coronavirus A59 E protein is palmitoylated. To understand the role of the conserved residues and the necessity of palmitoylation, three cysteines at positions 40, 44, and 47 were changed singly and in various combinations to alanine. Double- and triple-mutant E proteins resulted in decreased virus-like particle output when coexpressed with the membrane (M) protein. Mutant E proteins were also studied in the context of a full-length infectious clone. Single-substitution viruses exhibited growth characteristics virtually identical to those of the wild-type virus, while the double-substitution mutations gave rise to viruses with less robust growth phenotypes indicated by smaller plaques and decreased virus yields. In contrast, replacement of all three cysteines resulted in crippled virus with significantly reduced yields. Triple-mutant viruses did not exhibit impairment in entry. Mutant E proteins localized properly in infected cells. A comparison of intracellular and extracellular virus yields suggested that release is only slightly impaired. E protein lacking all three cysteines exhibited an increased rate of degradation compared to that of the wild-type protein, suggesting that palmitoylation is important for the stability of the protein. Altogether, the results indicate that the conserved cysteines and presumably palmitoylation are functionally important for virus production.

scholarly journals The glycosylation site in the envelope protein of West Nile virus (Sarafend) plays an important role in replication and maturation processes

2006 ◽  
Vol 87 (3) ◽  
pp. 613-622 ◽  
Author(s):  
J. Li ◽  
R. Bhuvanakantham ◽  
J. Howe ◽  
M.-L. Ng
Keyword(s):  
Envelope Protein ◽  
Phylogenetic Trees ◽  
Genomic Sequence ◽  
Infectious Clone ◽  
Glycosylation Site ◽  
Wild Type Virus ◽  
Envelope Gene ◽  
Wild Type ◽  
West Nile ◽  
Complete Genomic

The complete genome of West Nile (Sarafend) virus [WN(S)V] was sequenced. Phylogenetic trees utilizing the complete genomic sequence, capsid gene, envelope gene and NS5 gene/3′ untranslated region of WN(S)V classified WN(S)V as a lineage II virus. A full-length infectious clone of WN(S)V with a point mutation in the glycosylation site of the envelope protein (pWNS-S154A) was constructed. Both growth kinetics and the mode of maturation were affected by this mutation. The titre of the pWNS-S154A virus was lower than the wild-type virus. This defect was corrected by the expression of wild-type envelope protein in trans. The pWNS-S154A virus matured intracellularly instead of at the plasma membrane as shown for the parental WN(S)V.

scholarly journals N-glycosylation in the Pre-Membrane Protein Is Essential for the Zika Virus Life Cycle

Viruses ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 925
Author(s):  
Yong-Dae Gwon ◽  
Eva Zusinaite ◽  
Andres Merits ◽  
Anna K. Överby ◽  
Magnus Evander
Keyword(s):  
Zika Virus ◽  
Protein Trafficking ◽  
Nuclear Translocation ◽  
Infectious Clone ◽  
Glycosylation Site ◽  
Protein Glycosylation ◽  
Cell Trafficking ◽  
Virion Assembly ◽  
E Protein ◽  
The Impact

Asparagine (N)-linked protein glycosylation plays an important role in protein synthesis and modification. Two Zika virus (ZIKV) structural proteins, the pre-membrane (prM) and envelope (E) protein are N-glycosylated. The prM protein of all ZIKV strains contains a single N-linked glycosylation site, while not all strains contain an N-linked site in the E protein. Our aim was to examine the impact of prM and E N-linked glycosylation on ZIKV infectivity and cell trafficking. Using a ZIKV infectious clone, we found that when the N-glycan sites were removed, the prM- and the prM/E-double mutants did not produce an infectious virus in the supernatant. Further, by using ZIKV prME constructs, we found that N-glycosylation was necessary for effective secretion of ZIKV virions. The absence of the N-glycan on prM or E caused protein aggregation in the rough endoplasmatic reticulum (ER) compartment. The aggregation was more pronounced for the prM-mutation, and the mutant virus lost the ER-Golgi intermediate compartment (ERGIC) localization. In addition, lack of the N-glycan on prM induced nuclear translocation of CCAAT-enhancer-binding protein homologous protein (CHOP), an ER stress marker. To conclude, we show that the prM N-glycan is essential for the ZIKV infectious cycle, and plays an important role in viral protein trafficking, protein folding, and virion assembly.

Evaluation of flow-cytometry for the monitoring of infectious human rotavirus in water

1997 ◽  
Vol 35 (11-12) ◽  
pp. 451-453
Author(s):  
F. X. Abad ◽  
A. Bosch ◽  
J. Comas ◽  
D. Villalba ◽  
R. M. Pintó
Keyword(s):  
Flow Cytometry ◽  
Water Samples ◽  
Wild Type ◽  
Cell Monolayers ◽  
Naturally Occurring ◽  
Human Rotavirus ◽  
Faecal Samples

A method has been developed for the detection of infectious human rotavirus (HRV), based on infection of MA104 and CaCo-2 cell monolayers and ulterior flow cytometry. The sensitivity of the flow cytometry procedure for the cell-adapted HRV enabled the detection of 200 and 2 MPNCU in MA104 and CaCo-2 cells, respectively. Flow cytometry performed five days after infection of CaCo-2 enabled the detection of naturally occurring wild-type HRV in faecal samples and concentrated water samples.

scholarly journals Semi-Synthesis of Small Molecules of Aminocarbazoles: Tumor Growth Inhibition and Potential Impact on p53

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1637
Author(s):  
Solida Long ◽  
Joana B. Loureiro ◽  
Carla Carvalho ◽  
Luís Gales ◽  
Lucília Saraiva ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Small Molecules ◽  
Tumor Cells ◽  
Mutant P53 ◽  
Wild Type ◽  
Naturally Occurring ◽  
Growth Inhibitory ◽  
Growth Inhibitory Activity ◽  
Amino Derivatives ◽  
Carbazole Alkaloids

The tumor suppressor p53 is inactivated by mutation in approximately 50% of human cancers. Small molecules that bind and stabilize those mutants may represent effective anticancer drugs. Herein, we report the tumor cell growth inhibitory activity of carbazole alkaloids and amino derivatives, as well as their potential activation of p53. Twelve aminocarbazole alkaloids were semi-synthesized from heptaphylline (1), 7-methoxy heptaphylline (2), and 7-methoxymukonal (3), isolated from Clausena harmandiana, using a reductive amination protocol. Naturally-occurring carbazoles 1–3 and their amino derivatives were evaluated for their potential effect on wild-type and mutant p53 activity using a yeast screening assay and on human tumor cell lines. Naturally-occurring carbazoles 1–3 showed the most potent growth inhibitory effects on wild-type p53-expressing cells, being heptaphylline (1) the most promising in all the investigated cell lines. However, compound 1 also showed growth inhibition against non-tumor cells. Conversely, semi-synthetic aminocarbazole 1d showed an interesting growth inhibitory activity in tumor cells expressing both wild-type and mutant p53, exhibiting low growth inhibition on non-tumor cells. The yeast assay showed a potential reactivation of mutant p53 by heptaphylline derivatives, including compound 1d. The results obtained indicate that carbazole alkaloids may represent a promising starting point to search for new mutp53-reactivating agents with promising applications in cancer therapy.

scholarly journals Parkin regulates drug-taking behavior in rat model of methamphetamine use disorder

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Akhil Sharma ◽  
Arman Harutyunyan ◽  
Bernard L. Schneider ◽  
Anna Moszczynska
Keyword(s):  
Neural Substrates ◽  
Genetically Engineered ◽  
Wild Type ◽  
Therapeutic Approaches ◽  
Self Administration ◽  
Methamphetamine Use ◽  
New Therapeutic Approaches ◽  
Extended Access ◽  
High Doses ◽  
Methamphetamine Use Disorder

AbstractThere is no FDA-approved medication for methamphetamine (METH) use disorder. New therapeutic approaches are needed, especially for people who use METH heavily and are at high risk for overdose. This study used genetically engineered rats to evaluate PARKIN as a potential target for METH use disorder. PARKIN knockout, PARKIN-overexpressing, and wild-type young adult male Long Evans rats were trained to self-administer high doses of METH using an extended-access METH self-administration paradigm. Reinforcing/rewarding properties of METH were assessed by quantifying drug-taking behavior and time spent in a METH-paired environment. PARKIN knockout rats self-administered more METH and spent more time in the METH-paired environment than wild-type rats. Wild-type rats overexpressing PARKIN self-administered less METH and spent less time in the METH-paired environment. PARKIN knockout rats overexpressing PARKIN self-administered less METH during the first half of drug self-administration days than PARKIN-deficient rats. The results indicate that rats with PARKIN excess or PARKIN deficit are useful models for studying neural substrates underlying “resilience” or vulnerability to METH use disorder and identify PARKIN as a novel potential drug target to treat heavy use of METH.

scholarly journals Responsiveness to exogenous cAMP of a Saccharomyces cerevisiae strain conferred by naturally occurring alleles of PDE1 and PDE2.

Genetics ◽  
1993 ◽  
Vol 135 (2) ◽  
pp. 321-326 ◽  
Author(s):  
H Mitsuzawa
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Slow Growth ◽  
Loss Of Function ◽  
Wild Type ◽  
Triple Mutant ◽  
Apparent Absence ◽  
Camp Pathway ◽  
Naturally Occurring ◽  
Elevated Activity ◽  
Growth Phenotype

Abstract The Saccharomyces cerevisiae strain P-28-24C, from which cAMP requiring mutants derived, responded to exogenously added cAMP. Upon the addition of cAMP, this strain showed phenotypes shared by mutants with elevated activity of the cAMP pathway. Genetic analysis involving serial crosses of this strain to a strain with another genetic background revealed that the responsiveness to cAMP results from naturally occurring loss-of-function alleles of PDE1 and PDE2, which encode low and high affinity cAMP phosphodiesterases, respectively. In addition, P-28-24C was found to carry a mutation conferring slow growth that lies in CYR1, which encodes adenylate cyclase, and the slow growth phenotype caused by the cyr1 mutation was suppressed by the pde2 mutation. Therefore P-28-24C is fortuitously a pde1 pde2 cyr1 triple mutant. Responsiveness to cAMP conferred by pde mutations suggests that S. cerevisiae cells are permeable to cAMP to some extent and that the apparent absence of effect of exogenously added cAMP on wild-type cells is due to immediate degradation by cAMP phosphodiesterases.

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